Conventionally, a large amount of heat energy is released and lost as, for example, waste heat, light, etc. in various energy-using devices such as internal combustion engines including an automobile engine; heat exchangers including a boiler and air-conditioning equipment; motor generators including a power generator and a motor; and luminous devices including lightings.
Nowadays, recovery and recycling of released heat energy as an energy source has been required in view of energy conservation. To be specific, as such a system, for example, a power-generating system including a heat source which is able to produce temporal temperature variation, a first device (dielectric, etc.) in which polarization occurs by the piezoelectric effect, the pyroelectric effect, the Seebeck effect, etc. based on the temperature change of the heat source, and a second device (electrode, etc.) which is disposed to face the first device with the first device sandwiched therebetween in order to take out a net generating power from the first device has been proposed (ref: for example, the following Patent Document 1).